Sample injection arrangement for an analytical instrument

ABSTRACT

Sample injection in an analytical instrument comprises mechanically sealing a sample in a vessel, positioning the vessel within an injector of the instrument, mechanically forming an aperture in the vessel, and flowing a carrier gas through an apertured vessel.

United States Patent Frank et a1.

SAMPLE INJECTION ARRANGEMENT FOR AN ANALYTICAL INSTRUMENT Inventors!Peter Frank, Diasendorf/Meersburg (Bodensee); Dietrich Jentzsch; HelmutKurger, both of Uberlingen (Bodensee), all of Germany Assignee:Bodenseewerk Perkin-Elmer, Ulberlingen (Bodens'ee), Germany Filed: March13, 1970 Appl. No.: 18,378

Related US. Application Data Continuation of Ser. No. 719,037, Apr. 5,1968,

abandoned.

Foreign Application Priority Data April 12, 1967 Germany ..B 92023 US.Cl. ..73/422 GC- Int. Cl l ..G0ln 1/22, G01n 1/28 Field of Search..73/23. 1 422 GC; 222/5, 85,

I a 5 1 I 4 may 90 I Z r r l IIIIIIIIIIIIII' I 51 June 27, 1972 PrimaryExaminer-S. Clement Swisher Attorney-Edward R. Hyde, Jr.

[57] ABSTRACT Sample injection in an analytical instrument comprisesmechanically sealing a sample in a vessel, positioning the vessel withinan injector of the instrument, mechanically forming an aperture in thevessel, and flowing a carrier gas through an apertured vessel.

9 Claims, 9 Drawing Figures SAMPLE INJECTION ARRANGEMENT FOR ANANALYTICAL INSTRUMENT The present invention relates to a method andapparatus for the introduction of a sample under analysis to ananalytical instrument. The invention relates more particularly to amethod and apparatus for introducing a sample contained in an enclosedvessel to the instrument. I

Various samples which are to be analyzed such as samples which arevolatile or subject to'separation or other chemical change arepreferably introduced to an analytical instrument in an encapsulatedform. In a known sample injection technique, the sample is initiallysealed in a vessel and the vessel is positioned within an injectionsection of the instrument. Provision is made for permitting the sampleto escape from the vessel to an analysis section of the instrument. Inone sample introduction arrangement, the sample is deposited in a glasstube or'capillary tube which is then heat sealed. This tube ispositioned in the injection section of the instrument and is fractured,whereupon the sample escapes from the fractured vessel and is conveyedby a carrier gas to an analysis section of the instrument. In anotherarrangement, a metallic vessel is formed of indium, is filled with asample fluid by capillary action, andis sealed by mechanical force.After the vessel is positioned in an injection section of theinstrument, the vessel is heated to the molten state thereby freeing thesample, which is conveyed to an analysis section of the instrument.

The use of glass and metallic vessels adapted to be fractured and meltedrespectively introduces factors which substantially detract fromthe'value'of the sample analysis. With respect to a glass vessel, thesealing operation occurs through the application of heat at relativelyhigh temperatures which undesirably cause a change in the samplecomponents through thermal reactions. It has thus been customary toutilize an elongated glass vessel in order that the sample may bemaintained in a relatively cool temperature as the ends of the glass arebeing heat sealed. Such an arrangement, however, requires a relativelylarge injection chamber volume and as the sample escapes from the tube,the plug of sample material is extended substantially in a carrier gasstream and detracts from the value of the analysis. A vessel formed ofglass, in addition to exhibiting a disadvantageous, relatively lowthen'nal conductivity, will generally fracture into random fragments,the shape of which can introduce interfering flow resistances into acarrier gas stream and temporarily restrain portions of the sample frombeing swept away into the analytical section by the carrier stream.

Although a sample vessel formed of indium or other low melting pointmetal is sealed mechanically and avoids those disadvantages accompanyingthe sealing of a vessel by heat, it none the less is an unsuitablevessel for highly viscous and solid samples. Indium, in addition,exhibits other characteristics undesirable when used with an analyticalinstrument. For example, indium oxidizes at high temperatures and whenit exists in the liquid or molten state as it does in the injectionsystem, can react with halogens and sulphuric compounds. The liquid ormolten indium is generally collected in a tray, but this indium as aresult of oxide formations may function as a catalyst for samplesubstances passing across it. The use of other low melting point metalsis undesirable for similarreasons. Further, in a temperature range of338' to 356 F., indium can strongly diffuse into other metals, a factorwhich is critical in analytical instruments. For convenience, removal ofthe indium liquid metal or other low melting point metal from tivelylarge number of successive analyses have been performed rather thanafier each individual run. The evaporative volume thus varies inaccordance with the number of runs of the instrument made since the lastremoval of the indium. Individual sample injections are thereby carriedout under dissimilar conditions.

It is therefore an object of the present invention toprovide an improvedmethod for introducing encapsulated samples into an analyticalinstrument.

Another object of the invention'is the provision of an improvedapparatus for introducing encapsulated samples into an analyticalinstrument.

Another object of the invention is to provide a method of sampleinjection which avoids changes and reactions in the sample prior to andafter sample injection.

Another object of the invention is to provide a method for introducingfluid samples into enclosed vessels wherein defined flow conditions areestablished in the sample injector.

A further object of the invention is the provision of a relativelysimple and rapid method for injecting fluid and solid samples in closedvessels into an analytical instrument.

Still another object of the invention is to provide means forintroducing an encapsulated sample to an analytical instrument whichavoids one or more of the above-mentioned disadvantages.

Sample injection in accordance with the present invention comprisesmechanically sealing asample in a vessel,positioning the vessel withinan injector of the instrument, mechanically forming an aperture in thevessel, and flowing a carrier gas through an apertured vessel.

Injection apparatus in accordance with the present invention'includesevaporating means adapted to receive a closed mechanically deformablesample vessel. Means are provided for forming an aperture in the vesseland for rinsing the vessel with a carrier gas flowing to an analyticalsection of the instrument.

With-this method and apparatus, the vessel is mechanically sealed andthereby avoids sample changes which accompanied previous hightemperature sealing. Additionally, the pierced sample vessel can readilybe removed after each run and the introduction of a vessel melt into theevaporator is avoided. Further, piercing the vessel provides for awell-defined spatial form creating a substantially well-defined flowresistance for the carrier gas stream. Thus, substantially the sameconditions will prevail during each analysis.

These and other objects and features of the present invention willbecome apparent with reference to the following specifications and thedrawings, wherein:

FIG.' 1 is a view of a sample vessel prior to sealing;

FIG. 2a illustrates the vessel of FIG. 1 after sealing;

FIG. 2b is a sectional view taken along line 28-28 of FIG. 2a;

FIG. 3a illustrates segments of a tool utilized in a pre-forming step ofthe sealing operation for deforming the vessel of Which-the vessel isfabricated is generally effected after a rela- FIG. 1; 1 v

FIG. 3b is a view taken along line 3B-3B'of FIG. 30; I

FIG. 4 is an enlarged view illustrating sealing of the vessel of FIG. 1and shearing of residue material;

FIG. 5 is a sectional view of one embodiment of a sample injector inaccordance with the present invention;

FIG. 6 is a carrier gas flow diagram illustrating carrier gas glow forthe embodiment of FIG. 5; and

FIG. 7 is an alternative embodiment of the injector.

A sample vessel and the steps employed in its sealing will first bedescribed with reference to FIGS. 1-4. In FIG. 1 there is illustrated acup-shaped metallic vessel 10 for receiving a sample, the illustrationof FIG. 1 having an enlarged scale on the order of 10:1. An exemplaryvessel 10 has a wall thickness of 0.1 to 0.2 mm. and is fabricated bydeep drawing sheet 7 metal preferably formed of gold or aluminum.Handling of these vessels prior to introduction of a sample material isfacilitated by supporting the vessels in plug bores 12 of a workingplate 14. The plate 14 additionally serves to restrict excessiveflattening of the vessels as they are mechanically sealed. After avessel 10 is supplied with a sample substance to be analyzed and priorto the application of the actual sealing forces during the sealingprocedure, the vessel is pre-shaped by means of a pliers 16 illustratedin FIG. 3. This pre-shaping is initially provided in order to limit thewidth of the vessel at a on the opposite jaw. The recess 18 grips theupper end of the filled vessel 10 and this rim is compressed by means ofthe projection 20 engaging the recess 18. For proper compressive sealingin cold welding, a type of pinchers is used, the edges of which arereferenced by numerals 22 and 24 in FIG. 4. The edges of the pinchers 22and 24 form avery acute angle wedge upon contact with the vessel 10,thereby producing a clamp seal as is indicated at 26 in FIG. 2. FIG. 2illustrates a sealed vessel. The clamping or cold weld extends in anaxial direction about 15 mm and tapers gradually. The sheet metalremaining after the sealing, as illustrated by reference numeral 28 inFIG. 4, can be removed if desired or may be left on the vessel 10 forweighing purposes. An alternative arrangement for sealing the vessel lwhich avoids the application of heat to the vessel would be by theapplication of supersonic mechanical forces to the vessel.

FIG. illustrates a sample injector constructed in accordance withfeatures of the present invention. The sample injector includes atubular shaped evaporator indicated generally by the dashed rectangle 30and having a tubular member 32. The member 32 is heated by anyconventional means,'not illustrated, such as a heater coil positionedabout the tube. A hexagonal member 36 having internal threads 38 issoldered to the tube 32. The member 36 has soldered thereto a mountingplate 40 adapted for mounting the injector assembly to a chromatographor other analytical instrument. An insert assembly 42 extends into theevaporator tube 32. The assembly 42 comprises a tube 44 having an innerend thereof closed by a cap 46, a threaded member 50 and a coupling 52to a chromatographic column for example. The cap 46 supports a centrallylocated mandrel 48 and the threaded member 50 permits the assembly 42 tobe demountably screwed into the internal threads 38 of body 36. A gasketseal 54 is provided between the front face of the threaded member 50 andthe hexagonal piece 36. Six axial extending channels 56 are providedabout the mandrel 48 in the cap 46 and extend into the interior of thetube 44. Carrier gas enters the injector from an inlet line 58 and flowsin a narrow gap extending between the outer surface of tube 44 and theinner surface of evaporator tube.32. A weak carrier gas stream isthereby produced in the gap from right to left as viewed in FIG. 5, thuspreventing sample substance released in the evaporator as describedhereinafter from diffusing into this gap. A second carrier gas inletconnection 60 is provided near the column 52. The tube 44 is filled witha very fine-grained inert material constituting a flow resistance. Onesuch material is diatomaceous earth. As a result, the carrier gassupplied at the carrier gas inlet connection 60 flows substantially tothe separating column. Only a relatively small part of the stream passesthrough the tube 44 and through the inert filling, discharges throughthe channels 56, and with a dosing tube (described hereinafter) removed,flows to open atmosphere on the left side as viewed in FIG. 5. Thispartial stream has a desired rinsing effect for the system.

A tubular dosing tube housing 62 is soldered to the evaporator tube 32as shown in FIG. 5. This housing is surrounded by a water jacket 64 andcoolant water flowing in this jacket thereby establishes a relativelycool zone. A dosing tube 66 is inserted in the housing 62 and extendsinto the evaporator tube 32. The dosing tube 66 includes a shouldersegment 68 which, upon insertion of the dosing tube 66 in the housing 62is spring biased toward the left as viewed in FIG. 5 against a shoulder70 of the housing 62 by a helical spring 71. The dosing tube 66 supportsa silver jacket 72 at an end thereof. An elongated rod 74 is positionedwithin the dosing tube 66. An end portion of this rod includes a cavity75 for receiving and supporting a sample vessel in the injector. The rod74 supports a knurled knob 76 at an opposite end thereof and is adjustedaxially with respect to the dosing tube 66 by means of a threadedsegment 78 engaging a threaded segment of the dosing tube.

The dosing tube 66 is secured to the housing 62 by means of anadjustable bayonet lock 80. Reference numeral 82 designates a bayonetsleeve positioned about the housing 62 and gripping a nut 84. The nut 84is screwed onto the housing and includes a bayonet nose or stop 86. Thebayonet sleeve 82 is also screwed to the end of the dosing tube 66 andis secured in place by a lock nut 88. The nut 84 is secured in place bya lock nut 90. This bayonet lock permits the dosing tube 66 and the rod74 to be readily loosened and withdrawn from the evaporator tube 32 andfrom the housing 62. In addition, when the dosing tube 66 and the rod 74are mounted, the arrangement is adapted for forcing these members towardthe right for causing the mandrel 48 to pierce the sample vessel throughthe application of an axial force on the knob 76. As viewed in FIG. 5,the dosing tube and shaft 74 are shown in their right-most position.Under the influence of the bias spring 71, the dosing tube 66 and therod 74 are automatically returned to the left-most position upon theremoval of the axial force at knob 76.

A carrier gas is introduced to the evaporator tube 32 through an inlettubing 92, which opens into a recessed jacket space 94 of the evaporatortube. This jacket space 94 communicates through a radial bore 96 with ajacket space 98 formed by a recess of the rod 74 and an inner surface ofthe dosing tube 66. The jacket space 98 in turn communicates via aradial bore 100 in tube 74 with an axial bore 102. The bore 100communicates with an axial bore 102, the latter bore extending to thebottom of the sample vessel receiving means 75. The rod 74 and thehousing 62 include grooves 101 and 103 respectively for supportingO-rings. These O-rings provide a gas seal between the rod 74 and thedosing tube 66, and between the dosing tube 66 and the housing 62. Thecarrier gas flow paths with the injector of FIG. 5 are illustrated inFIG. 6. A carrier gas is derived from a source 105 and flows via asupply line 104 to two branches, 106 and 108. In each of these branchesthere is provided an adjustable restrictor 1 10 and 112, respectively,and a solenoid operated valve 114 and 116, respectively. The firstbranch 106 divides downstream of the restrictor 114 into a first streamwhich flows to the inlet 92 of the evaporator 30 via an adjustable gasflow restrictor 118. Another part of the stream flows to the inlet 58 ofthe evaporator 30 via a gas restrictor 120. Carrier gas also flows inthe second branch 108 to inlet 60 and leads substantially directly tothe separating column 122, for example, of an analytical instrument.

The injector arrangement thus far described functions in the followingmanner. A sample is sealed in a vessel 10 in a manner describedhereinbefore. The bayonet lock 80 is loosened and the dosing tube 66 androd 74 are then withdrawn from the evaporator tube 30 from the housing62. The sealed sample vessel is then inserted in the end of the dos ingtube 66 inside of the silver jacket 72 and its position in the receivingmeans 75 of the rod 74. The vessel is positioned in a manner forproviding that the sealed end 26 is adjacent the channel 102 of the rod74. The rod 74 is then adjusted axially relative to the dosing tube 66by rotating knob 76 in a manner for providing that pressing of thedosing tube 66 fully into its right-hand end position will cause thevessel 10 to be pierced by the mandrel 48 on two opposite sides. Thedosing tube 66 and rod 74 are then remounted, the bayonet lock issecured and the vessel 10 is pierced by pressing knob 76 in an axialdirection. Upon release of the dosing tube 66, the dosing tube 66 andthe rod 74 rebound toward the left in FIG. 5 under the influence of thespring 71. The valve 116 is open and the solenoid valve 114 is closed.The carrier gas then flows substantially directly to the column 122. Aslong as the dosing tube 66 is demounted from the injector, a portion ofthe carrier stream to inlet 60 discharges into the atmosphere as arinsing stream via tube 44, tube 32 in the housing 62. When the dosingtube 66 and the sample vessel are mounted, the sample column temporarilyretained in the area of the cooling means 64 until a stable zero line isestablished. The closing tube 66 is then forced toward the right and thevessel 10 is pierced by the mandrel 48. At the same time, a solenoidvalve 116 is closed and the valve 1 14 is opened, causing the carriergas to flow via the first branch 106. A small portion of this carriergas flows via the carrier gas inlet 58 and inhibits the sample fromdiffusing in the gap between the tube 44 and the evaporator tube 32, asindicated hereinbefore. However, a major portion of the carrier gasflows via the inlet 92 and through the channel 102 to the bottom of thereceiving means 75. This gas flows through the bilaterally piercedsample vessel and through the channels 56 and the tube 44 to the column122. The tube 44 with the inert filling material also functions at thesame time as a homogenizer. Some carrier gas stream also passes throughthe gap between the dosing tube 66 and the evaporator tube 32 to theO-ring groove 101 and prevents sample diffusion in this gap. Therestrictors 110 and 112 of FIG. 6 are adjusted for providing that thecarrier gas flow rate in the separating column 22 remains unaltered whenthe carrier gas flows either in branch 108 or branch'l06. Therestrictors thus compensate for any change in flow impedance introducedby the resistance of the pierced vessel prior to and after the pierc- Inthe alternative embodiment of FIG. 7, elements corresponding to thosedescribed with respect to FIG. 5 bear the same reference numerals. Thesame carrier gas flow paths described with respect to FIG. 6 exist withrespect to the em bodiment of FIG. 7. However, the pierced vessel is notrinsed as in FIG. 5, and the vessel 10 is pierced and flushed from oneside. When the carrier gas flows in the branch 106, major carrier flowis now supplied to the carrier gas inlet connection 58 rather than 92 aswas the case with FIG. 5. The tube 44 is formed with a longitudinalgroove 124 through which the carrier gas flows. Carrier gas flows fromthis groove to a radial channel 126 which terminates in a central bore128 of the mandrel 48. The radial channel 126 is guided between theaxial channels 56 by a web. With this embodiment, only a relativelysmall carrier gas is applied to the injector stream which as describedhereinbefore functions to inhibit diffusion of the sample substances inthe gap between the dosing tube 66 and the-evaporator tube 32. In theembodiment of FIG. 7, the sample vessel 10 is inserted in the samemanner as described with respect to FIG. 5. The rod 7 is adjusted in anaxial direction by knob 76 and relative to the dosing tube in a mannerfor providing that the mandrel 48 pierces the vessel on only one side.The carrier gas which then passes through the central bore 128 of themandrel 48 expells the sample from the vessel and thus carries the samealong through the opening 56 and the tube 44 toward the separatingcolumn 122.

Carrier gas switching can be accomplished automatically upon piercing ofthe vessel 10. An automatic switching arrangement is illustrated in FIG.6. This arrangement includes a source of electrical potential 140,'aswitch 142 operated when the vessel is pierced and actuated by the axialmotion of knob 76 for example, and a conventional circuit means 144 forholding in the energized solenoid 114 until the instrument operatorinterrupts energization of the solenoid.

Thus a method and arrangement facilitating the introduction of samplesin sealed vessels to an analytical instrument has been described. Themethod and arrangement advantageously avoid many of the problemsenumerated hereinbefore which accompany the use of glass and low meltingpoint vessel materials thereby enhancing the value of the analysrs.

While we have illustrated and described a particular embodiment of ourinvention, it will be understood that various modifications may be madetherein without departing from the spirit of the invention and the scopeof the appended claims.

We claim:

1. Sample injection apparatus for introducing a sample contained in asealed vessel to a gas chromatographic instrument comprising:

means for supporting a mandrel in a stationary position and a samplevessel formed of metal in an enclosed injection volume and for impellingsaid vessel against said stationary mandrel in a manner for causing saidmandrel to effect a non-shattering piercing of said vessel;

a metal sample vessel supported by said support means;

said support means including a demountable elongated member adapted forsupporting said vessel at an extremity thereof within said injectionvolume and for impelling said vessel against said mandrel to formapertures in oppositely disposed segments of the vessel,

means providing a first carrier fluid flow path between said injectionvolume and the separating column of the gas chromatographic instrument;and,

means including said elongated member for defining a carrier gas flowpath between a source of carrier gas and said vessel in said injectionvolume for rinsing a pierced vessel of sample material.

2. Sample injection apparatus for introducing a sample contained in asealed vessel to a gas chromatographic instrument comprising:

means for supporting a mandrel in a stationary position and a samplevessel formed of metal in an enclosed injection volume and for impellingsaid vessel against said stationary mandrel in a manner for causing saidmandrel to effect a non-shattering piercing of said vessel;

a metal sample vessel supported by said support means;

means providing a first carrier fluid flow path between said injectionvolume and the separating column of the gas chromatographic instrument;

means for coupling a source of carrier gas to the analytical instrumentat a coupling point in said first flow path intermediate said injectionapparatus and the instrument; and,

means establishing a carrier fluid flow path between said source ofcarrier gas and said vessel in said injection volume for rinsing apierced vessel of sample material.

3. The injection apparatus of claim 2 wherein said means for providingsaid first carrier fluid flow path includes a fiuid fiow impedancepositioned in said path upstream of said carrier gas coupling point,said flow impedance providing a fiow passage for vaporized sampletransported in said carrier gas.

4. The injection apparatus of claim 3 wherein said flow resistancecomprises a plurality of particles.

5. The injection apparatus of claim 2 including means for alternativelycoupling a source of carrier gas between said position in said firstcarrier fluid flow path intermediate said flow impedance and theinstrument and to said means for conveying a carrier fluid to saidvessel.

6. A sample injection apparatus for introducing a sample contained in asealed vessel to an analytical instrument comprising:

a tubular evaporator member adapted to receive an injector assembly atone end thereof and a dosing tube from an opposite end thereof;

an injector assembly including a tubular insert member containing aplurality of particles forming a carrier fluid flow resistance, aclosure member positioned at an inner end of said insert and having achannel formed thereon extending generally in an axial direction, amandrel supported by said closure member and extending away from saidinsert member, and means supporting said assembly within said evaporatortube in fluid-tight relationship therewith;

a dosing housing having a generally cylindrical bore coupled to saidevaporator member;

a tubular dosing member positioned in said housing and extending intosaid evaporator tube;

an elongated generally cylindrically shaped support rod positionedwithin the dosing tube and adapted for relative adjustment therewith inan axial direction, said rod having an end segment thereof adapted forsupporting a sample vessel at one end thereof within said evaporatortube;

means for biasing said support rod in a spaced apart position from saidmandrel;

means for securing said dosing member to said housing and for providingdisplacement of said dosing member in an axial direction;

said support rod having an axial channel formed therein communicatingwith the vessel support end segment of said rod; and

means adapted for coupling to a source of carrier fluid and forproviding a fluid flow path to said channel of said support rod.

7. The injection apparatus of claim 6 wherein said evaporator tube andinsert member are physically proportioned for providing a carrier fluidflow volume intermediate an outer surface of said insert and an innersurface of said evaporator tube and means adapted for coupling to asource of carrier fluid are provided for introducing a carrier fluid tosaid flow volume intermediate said insert and injector member.

8. The injection apparatus of claim 7 wherein said means for securingsaid dosing member to said housing comprise a bayonet lock.

9. A method for injecting a sample into an analytical instrumentcomprising the steps of:

introducing a sample material into a mechanically deformable metalvessel;

applying a mechanical pressure to said vessel for cold-welding thevessel to form an enclosed container;

positioning the enclosed vessel in an enclosed injection volume;

piercing the vessel in the injection volume; and

flowing a carrier gas in the pierced vessel and from the vessel to ananalytical instrument.

1. Sample injection apparatus for introducing a sample contained in asealed vessel to a gas chromatographic instrument comprising: means forsupporting a mandrel in a stationary position and a sample vessel formedof metal in an enclosed injection volume and for impelling said vesselagainst said stationary mandrel in a manner for causing said mandrel toeffect a non-shattering piercing of said vessel; a metal sample vesselsupported by said support means; said support means including ademountable elongated member adapted for supporting said vessel at anextremity thereof within said injection volume and for impelling saidvessel against said mandrel to form apertures in oppositely disposedsegments of the vessel, means providing a first carrier fluid flow pathbetween said injection volume and the separating column of the gaschromatographic instrument; and, means including said elongated memberfor defining a carrier gas flow path between a source of carrier gas andsaid vessel in said injection volume for rinsing a pierced vessel ofsample material.
 2. Sample injection apparatus for introducing a samplecontained in a sealed vessel to a gas chromatographic instrumentcomprising: means for supporting a mandrel in a stationary position anda sample vessel formed of metal in an enclosed injection volume and forimpelling said vessel against said stationary mandrel in a manner forcausing said mandrel to effect a non-shattering piercing of said vessel;a metal sample vessel supported by said support means; means providing afirst carrier fluid flow path between said injection volume and theseparating column of the gas chromatographic instrument; means forcoupling a source of carrier gas to the analytical instrument at acoupling point in said first flow path intermediate said injectionapparatus and the instrument; and, means establishing a carrier fluidflow path between said source of carrier gas and said vessel in saidinjection volume for rinsing a pierceD vessel of sample material.
 3. Theinjection apparatus of claim 2 wherein said means for providing saidfirst carrier fluid flow path includes a fluid flow impedance positionedin said path upstream of said carrier gas coupling point, said flowimpedance providing a flow passage for vaporized sample transported insaid carrier gas.
 4. The injection apparatus of claim 3 wherein saidflow resistance comprises a plurality of particles.
 5. The injectionapparatus of claim 2 including means for alternatively coupling a sourceof carrier gas between said position in said first carrier fluid flowpath intermediate said flow impedance and the instrument and to saidmeans for conveying a carrier fluid to said vessel.
 6. A sampleinjection apparatus for introducing a sample contained in a sealedvessel to an analytical instrument comprising: a tubular evaporatormember adapted to receive an injector assembly at one end thereof and adosing tube from an opposite end thereof; an injector assembly includinga tubular insert member containing a plurality of particles forming acarrier fluid flow resistance, a closure member positioned at an innerend of said insert and having a channel formed thereon extendinggenerally in an axial direction, a mandrel supported by said closuremember and extending away from said insert member, and means supportingsaid assembly within said evaporator tube in fluid-tight relationshiptherewith; a dosing housing having a generally cylindrical bore coupledto said evaporator member; a tubular dosing member positioned in saidhousing and extending into said evaporator tube; an elongated generallycylindrically shaped support rod positioned within the dosing tube andadapted for relative adjustment therewith in an axial direction, saidrod having an end segment thereof adapted for supporting a sample vesselat one end thereof within said evaporator tube; means for biasing saidsupport rod in a spaced apart position from said mandrel; means forsecuring said dosing member to said housing and for providingdisplacement of said dosing member in an axial direction; said supportrod having an axial channel formed therein communicating with the vesselsupport end segment of said rod; and means adapted for coupling to asource of carrier fluid and for providing a fluid flow path to saidchannel of said support rod.
 7. The injection apparatus of claim 6wherein said evaporator tube and insert member are physicallyproportioned for providing a carrier fluid flow volume intermediate anouter surface of said insert and an inner surface of said evaporatortube and means adapted for coupling to a source of carrier fluid areprovided for introducing a carrier fluid to said flow volumeintermediate said insert and injector member.
 8. The injection apparatusof claim 7 wherein said means for securing said dosing member to saidhousing comprise a bayonet lock.
 9. A method for injecting a sample intoan analytical instrument comprising the steps of: introducing a samplematerial into a mechanically deformable metal vessel; applying amechanical pressure to said vessel for cold-welding the vessel to forman enclosed container; positioning the enclosed vessel in an enclosedinjection volume; piercing the vessel in the injection volume; andflowing a carrier gas in the pierced vessel and from the vessel to ananalytical instrument.